title: Apical extrusion of bacteria when using reciprocating single-file and rotary multifile instrumentation systems.
abstract: OBJECTIVE
  To evaluate ex vivo, apical bacterial extrusion associated with two reciprocating single-file systems (WaveOne and Reciproc) compared with a conventional multifile rotary system (BioRace).
  
  
  METHODS
  Forty-five human single-rooted mandibular incisors were used. Endodontic access cavities were prepared, and root canals were contaminated with an Enterococcus faecalis suspension. Following incubation at 37 °C for thirty days, the contaminated teeth were divided into three groups of 15 specimens each (G1 - Reciproc, G2 - WaveOne and G3 - BioRace). Positive and negative controls consisted of 5 infected teeth and 3 uninfected incisors that were instrumented with one of the tested NiTi systems, respectively. Bacteria extruded from the apical foramen during instrumentation were collected into vials containing 0.9% NaCl. The microbiological samples were taken from the vials and incubated in brain heart agar medium for 24 h. The resulting bacterial titre, in colony-forming units (CFU) per mL, was determined, and these data were analysed by Wilcoxon matched-pairs signed rank test and Kruskal-Wallis H-test. The level of significance was set at α = 0.05.
  
  
  RESULTS
  No significant difference was found in the number of CFU between the two reciprocating systems (P = 0.41). The conventional multifile rotary system group was associated with significantly higher CFU than both of the two reciprocating groups (P = 0.01).
  
  
  CONCLUSIONS
  All instrumentation systems extruded bacteria beyond the foramen. However, both reciprocating single-file systems extruded fewer bacteria apically than the conventional multifile rotary system.
authors.affiliation: Proclin Department, School of Dentistry, Rio de Janeiro State University, Rio de Janeiro, Brazil.
authors.forename: J M
authors.initials: JM
authors.lastname: Tinoco
authors.forename: G
authors.initials: G
authors.lastname: De-Deus
authors.forename: E M B
authors.initials: EM
authors.lastname: Tinoco
authors.forename: F
authors.initials: F
authors.lastname: Saavedra
authors.forename: R A S
authors.initials: RA
authors.lastname: Fidel
authors.forename: L M
authors.initials: LM
authors.lastname: Sassone
mesh_terms: D003762:Dental Instruments; D003786:Dental Pulp Cavity / Q000382:microbiology; D013293:Enterococcus faecalis / Q000302:isolation & purification*; D006801:Humans
keywords: apical extrusion; bacteria; engine-driven techniques; rotatory instruments